In the book Cialdini and his co-authors outline a series of experiments on the cards in hotel bathrooms attempting to persuade us to reuse the towels. The standard appeal on these cards is to our concern for the environment. The authors experimented with changes to the wording on these cards. Here’s what they found:

Guests who were told that most other guests reused their towels, were 26% more likely to reuse their towels than those who saw the standard message.

Guests who were told that most other guests who stayed in their particular room, were 33% more likely to reuse their towels than those who saw the standard message.

So what does this mean when you are seeking to persuade in a presentation.

1. If other people are doing or supporting what you want your audience to do, bring that into your presentation. Here are some ways of doing that:

find an endorsement from a credible expert that your audience knows and trusts

use testimonials from people similar to your audience

develop case studies of people/organisations that are similar to your audience

use statistics to show how many people are using your product or taking action (this is taking it from the micro to the macro).

2. Be subtle about the way that you do this. If you tell people “Of course, you’re going to be persuaded by what other people have done” this will backfire on you. When Cialdini asked people whether other people’s behaviour influences their own, they insisted that it did not. We don’t like to think of ourselves as simply doing what other people do.

3. If you’re trying to persuade your audience not to do something, don’t focus on the number of people who are doing it. The implicit message that people will take away is that other people are doing it, and therefore it’s OK. Cialdini gives an example of a sign at Arizona’s Petrified Forest National Park which said:

Your heritage is being vandalized every day by theft losses of petrified wood of 14 tons a year, mostly a small piece at a time.

The book authors experimented with these signs. They used marked pieces of petrified wood along the trails to see how much visitors would steal. When there was no sign 2.92% of the pieces were stolen. When the sign above was used, 7.92% of the pieces were stolen! So despite the good intentions of the National Park management they were actually promoting the stealing of petrified wood.

Persuasion based on what other people do is called using “Social Proof”. As you can see it’s a powerful persuasive tool for using – with care and discretion – in your presentations.

In the next post in this series, I’ll look at the surprising results that Cialdini and his co-authors report on the use of negativity in persuasive messages.